Exterior finishing systems for building constructions include brick or masonry, aluminum siding, wooden siding, sheet metal panels, and stucco. The popularity of stucco finishes has recently increased partially due to the introduction of prefinished moulding components, prefabricated panels and other stucco finished components which have an insulating foam core coated with weatherproof coating.
Stucco finishes have traditionally been associated with the architectural styles of southern Europe, South and Central America and other relatively warm climates, however, modern stucco products have been used in northern climates as well with equal success. In Canada and the northern United States traditionally buildings have been clad with brick, metal or wood siding, although stucco finishes are on the increase.
The widespread adoption of stucco construction has been inhibited largely due to the relatively high cost and short summer period in northern climates. Stucco finishing requires highly skilled labour and dry warm weather due to the conventional practice of applying the entire multiple layer stucco coating by hand on site. Typically, stucco mouldings are affixed to a concrete block or wooden wall, a reinforcing mesh is then applied to the wall, a coarse base layer of stucco and then one or two finish coats of fine stucco are applied by hand.
To reduce the labour component, prefabricated and precoated stucco panels and moulding have been provided, however, conventional methods still require the entire surface to be finish stucco coating to be applied by hand on site. The appearance of the final coating is critical to the overall result and so highly skilled workers are required to ensure consistent colour, thickness, finish roughness etc. Since moulding, panels and other prefinished components may have slightly different exterior coloured or textured finishes, it is common to integrate all components visually by applying the final finish coating of stucco on site.
As a result of the high labour content involved in stucco finishing, other conventional finishes are largely preferred by builders, such as brick and siding. The brick and metal siding come to the site usually in a completely finished state requiring only cutting and installation to produced a complete exterior finish. The level of skill is lower than stucco, and the methods of construction are generally familiar to workers. For these reasons, small scale projects done by individual property owners or small contractors don't often include stucco, but rather tend to include wooden or metal siding which do not require the same skill or tools.
Never the less, architects and owners often prefer the appearance of stucco, and wish to benefit from some of its advantages. Stucco is very easily integrated with other finishes and is relatively lightweight. By including a layer of foam in the prefabricated stucco coated panels and mouldings, a significant degree of insulating value can be easily added. These advantages result in stucco use in many renovation or addition projects. Stucco also gives a modern clean and stylish impression whereas metal or wood siding appears on relatively low cost housing, and projects an associated image.
Stucco is the traditional method of exterior finishing in many southern climates, partly due to the relatively high cost of alternative finish materials such as wood or metal in those parts of the world. In contrast, stucco uses much less expensive materials, such as sand and cement. Even in southern markets, the speed of traditional stucco finishing and labour intensive methods involved result in significant construction costs and time involved.
Stucco cannot be properly applied in wet weather except in a sheltered enclosure and requires a period of time in relatively warm air after application to cure properly. Stucco is applied as a wet cement mixture and therefore cannot be applied in freezing weather or heavy rain. Scaffolding is required to gain access to the wall to be coated with traditional stucco, and to store materials. The cost of heating stucco after application to prevent freezing overnight renders the acceptance of stucco limited especially in colder climates.
Conventional prefabricated panels in part address these problems by providing a partially finished panel which is final finish coated on site. However in many southern climates, labour is still relatively cheap compared to the costs of factory prefabrication and transport of materials to a building site. As a result, the adoption of prefabricated panels has not penetrated beyond large volume building construction projects such as hotels, commercial and industrial buildings. Homes coated with stucco remain largely built with traditional labour intensive methods and locally available materials.
It is desirable therefore to produce a finished stucco finish by methods which reduce the level of skill and the time involved.
It is also desirable to produce stucco finishes with a final cost competitive with conventional finishing systems, including traditionally installed stucco, brick, wood or metal siding.
It is desirable to produce a lightweight durable stucco building product which is simple to understand, uses commonly available tools and building methods, so that relatively unskilled people, such as do-it-yourself homeowners or those in developing countries, can easily complete a project.
It is also desirable to produce a stucco product which is substantially finished to reduce on site labour and can be installed in various weather conditions, without specialized tools or complex installation methods.